GENEVA: The World Health Organization is sending more than one million polio vaccines to Gaza to be administered over the coming weeks to prevent children being infected after the virus was detected in sewage samples, its chief said on Friday. “While no cases of polio have been recorded yet, without immediate action, it is just a matter of time before it reaches the thousands of children who have been left unprotected,” Director-General Tedros Adhanom Ghebreyesus said in an opinion piece in Britain’s The Guardian newspaper.